1. Field of the Invention
This invention relates to packaging machines and more particularly to machines for wrapping an object with a sheet material.
2. Description of the Prior Art
In recent years, the art of packaging and containerizing items has made substantial advances and has produced highly sophisticated machines for accomplishing various packaging tasks. In general, the art attempts to package items in a more superior fashion and at a more economical price. The cost of packaging is generally determined by two factors. The first factor is the material cost involved in packaging the item. Accordingly, the art attempts to reduce the amount of material or to substitute a less expensive material without sacrificing packaging quality or strength. The second factor for providing an economical package is the packaging operating costs involved in actually packaging the object. In general, the packaging or containerization of an item or container is done automatically by machine. Accordingly, the packaging operating cost is primarily determined by the rate at which the machine can be operated and the initial cost of the packaging machine.
One of the more popular methods of packaging is through the use of a heat shrinkable plastic material. In general, there are two types of heat shrinkable plastic packages. The first package involves wrapping the item about two sides with the sheet material extending over the top and under the bottom of the container. The container is then passed through a heated region whereat the material shrinks to conform to the outer configuration of the container. The second package uses the heat shrinkable plastic material on only two sides and the top of the item. The second type package saves approximately one-half of the material cost over the first package.
The art has developed various machines for wrapping an object with a heat shrinkable sheet material for a heat shrink packaging process. Unfortunately, the machines of the prior art have not satisfied the existing needs of the art. In general, the prior art machines are only able to accommodate a specific size container. If a different size container is to be packaged, substantial modification and adjustment of the machine is required prior to the efficient operation of the device. In addition, the prior art has not developed a machine which is compatible for use with both the full wrap of heat shrinkable material and the upper wrap of heat shrinkable material of the container. A further disadvantage of the prior art machines was the relatively slow operation speed.
Therefore it is an object of this invention to provide an apparatus which overcomes the aforementioned inadequacies of the prior art devices and provides an improvement which is a significant contribution to the advancement of the packaging art.
Another object of this invention is to provide a device for wrapping a sheet material about a portion of an object comprising a sealing member having a plurality of sealing elements rotatably mounted about a common hub wherein the sealing material is draped over the object between two adjacent sealing elements.
Another object of this invention is to provide a device for wrapping a sheet material about an object comprising a first sealing member having a plurality of sealing elements rotatably mounted about a common axis in combination with a second sealing member slidably mounted for reciprocal movement in a direction along a line extending through the common axis.
Another object of this invention is to provide a device for wrapping a sheet material about an object which device is capable of simultaneously wrapping the sheet material over the upper region and the bottom region of the object. The device may be quickly modified to dispose the sheet material over only the two opposed sides and the upper region of the object.
Another object of this invention is to provide a device for wrapping a sheet material about an object incorporating a heat sealing means removably mounted to a subframe for enabling rapid interchange of the heat sealing means in the event of failure of the heat sealing element.
Another object of this invention is to provide a method of wrapping a sheet material about a portion of an object which results in superior performance over the prior art machines.
Another object of this invention is to provide a device for wrapping a sheet material about an object which device can be economically operated and easily cleaned for wrapping food products.
Another object of this invention is to provide a method of wrapping a sheet material about a portion of an object which increases the productivity relative to the prior art machines.
The foregoing has outlined some of the more pertinent objects of the invention. These objects should be construed to be merely illustrative of some of the more prominent features and applications of the intended invention. Many other beneficial results can be attained by applying the disclosed invention in a different manner or modifying the invention within the scope of the disclosure. Accordingly, other objects and a fuller understanding of the invention may be had by referring to the summary of the invention and the detailed description describing the preferred embodiment in addition to the scope of the invention defined by the claims, taken in conjunction with the accompanying drawings.